linux-kernel - [PATCH v8 4/6] arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time

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Message-ID: <1389206998-27875-4-git-send-email-stefano.stabellini@eu.citrix.com>
Date:	Wed, 8 Jan 2014 18:49:56 +0000
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	<xen-devel@...ts.xensource.com>
CC:	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <konrad.wilk@...cle.com>,
	<marc.zyngier@....com>, <will.deacon@....com>,
	<Stefano.Stabellini@...citrix.com>, <Ian.Campbell@...rix.com>,
	<linux@....linux.org.uk>, <olof@...om.net>, <arnd@...db.de>,
	<catalin.marinas@....com>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	<nico@...aro.org>, <cov@...eaurora.org>, <Catalin.Marinas@....com>
Subject: [PATCH v8 4/6] arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

Introduce CONFIG_PARAVIRT and PARAVIRT_TIME_ACCOUNTING on ARM64.
Necessary duplication of paravirt.h and paravirt.c with ARM.

The only paravirt interface supported is pv_time_ops.steal_clock, so no
runtime pvops patching needed.

This allows us to make use of steal_account_process_tick for stolen
ticks accounting.

Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
CC: will.deacon@....com
CC: nico@...aro.org
CC: marc.zyngier@....com
CC: cov@...eaurora.org
CC: arnd@...db.de
CC: olof@...om.net
CC: Catalin.Marinas@....com

---

Changes in v7:
- ifdef CONFIG_PARAVIRT the content of paravirt.h.
---
 arch/arm64/Kconfig         |   20 ++++++++++++++++++++
 arch/arm64/kernel/Makefile |    1 +
 2 files changed, 21 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6d4dd22..d1003ba 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -212,6 +212,25 @@ config HAVE_ARCH_TRANSPARENT_HUGEPAGE
 
 source "mm/Kconfig"
 
+config PARAVIRT
+	bool "Enable paravirtualization code"
+	---help---
+	  This changes the kernel so it can modify itself when it is run
+	  under a hypervisor, potentially improving performance significantly
+	  over full virtualization.
+
+config PARAVIRT_TIME_ACCOUNTING
+	bool "Paravirtual steal time accounting"
+	select PARAVIRT
+	default n
+	---help---
+	  Select this option to enable fine granularity task steal time
+	  accounting. Time spent executing other tasks in parallel with
+	  the current vCPU is discounted from the vCPU power. To account for
+	  that, there can be a small performance impact.
+
+	  If in doubt, say N here.
+
 config XEN_DOM0
 	def_bool y
 	depends on XEN
@@ -220,6 +239,7 @@ config XEN
 	bool "Xen guest support on ARM64 (EXPERIMENTAL)"
 	depends on ARM64 && OF
 	select SWIOTLB_XEN
+	select PARAVIRT
 	help
 	  Say Y if you want to run Linux in a Virtual Machine on Xen on ARM64.
 
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 5ba2fd4..1dee735 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -18,6 +18,7 @@ arm64-obj-$(CONFIG_SMP)			+= smp.o smp_spin_table.o
 arm64-obj-$(CONFIG_HW_PERF_EVENTS)	+= perf_event.o
 arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT)+= hw_breakpoint.o
 arm64-obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
+arm64-obj-$(CONFIG_PARAVIRT)		+= paravirt.o
 
 obj-y					+= $(arm64-obj-y) vdso/
 obj-m					+= $(arm64-obj-m)
-- 
1.7.10.4

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